i've had a really bad run lately with a Corsair 650TX (versions 1 and 2). to cut a very long story short, i bought the PSU just before discovering this site, and within a week of my fourth replacement, the PSU has just died. so i have had enough and don't want another replacement as i have wasted enough time.

so i'm looking for some advice on a suitable PSU for my system. i am happy with the other parts and would like a reliable and quiet PSU (the Corsair seemed way too loud, and was by far the loudest component in my system).

so pretty simple really. i use the PC mainly for work. often the CPU is under 100% load for hours at a time. in the future i may use the GPU for realtime rendering, in which case it too will be at 100% load for a number of hours at a time. in general, even when CPU is at 100% load, the temps rarely go above 60deg (CPU has a Noctua heatsink and 2 x Noctua fans).

please let me know if you need to know anything else and a quick response is appreciated as i have to get this fixed asap.

i was looking at the Seasonic x660 but have no idea if this is OTT or maybe even not enough? reading some of the articles and threads here it seems that these PSUs are over spec'ed in many cases, although i would rather have more power than needed and less noise than the other way around.

I've been wary of the TX series due to multiple makers and people getting some really poor units QC wise.

The vertical fan position shouldn't be a problem. The system's draw is probably around 320 W tops so anything from 400 W rated and up should do. I'm personally a fan of Nexus power supplies, the acoustics haven't let me down and even the Value model has been running problem-free for about four or five years now. Seasonic is certainly a reputable brand, and they have the leading 5 year warranty on offer in exchange for the hefty price tags.

The semipassive X660 is probably a very nice unit, but you certainly should not need anything above 500, never mind 600 W, with just 1 CPU, 1 GPU and 1 HDD when the units are 80 Plus certified. For long runs under stress you'll want to find the individual ratings and fan controller curves of the PSUs.

For comparison, I have the Nexus RX-5300 in my current rig. According to its specs, http://www.nexustek.nl/Nexus_RX-5300_Mo ... y_530W.htm, it should gain no more than 2 dB(A) to its very benign baseline all the way up to 60 % load (318 W). Incidentally that load is also where the PSU works at its most efficient. If you are planning to upgrade to a hungrier GPU, you might want to bump the wattage up a notch to stay riding the efficiency peak and fan controller's Low range.

Note on the SPCR list: you can find Seasonic X series (they are all named collectively in the X-650 review summary) in the Editor's Choice section and the Nexus PSUs I mentioned in the Recommended section (substitute RX-8500 with the RX-5300 if you will). That says it all really - one is good, but the other is even better. It's all down to the price you're willing to pay and what features you want, warranty included.

An aside: some people, myself included, have run into buzzy, squealy or otherwise noisy Seasonics. I did not want to mention this first off as I still hold Seasonic in high regard and put this down to (very limited) sample variance, although my results were consistent with two units (1 initial, 1 RMA; S12-II 430 W).

i would go with the Seasonic as it is fanless for much of the time, but read a number of times that there might be some buzzing.

the priority for me is quiet operation, and i absolutely don't want coil whine or buzzing. i would rather hear a very faint fan noise.

so based on that, would you suggest going for the Nexus 6300 or the Seasonic 660?

and one other question. the Corsair i had (and 4 of which i tried and had defects of some kind) is supposed to be made by Seasonic (though it is quite a bit cheaper), so why should the 'real' Seasonic be any different? what components do Corsair change on the Seasonic to bring the price down?

i can't seem to find the Nexus RX 5300 in the UK, though i can find the 6300 - anything known issues with this one? [...] so based on that, would you suggest going for the Nexus 6300 or the Seasonic 660?

The Nexus RX-6300 should be no different overall, just a teeny tiny bit louder according to the graphs on Nexus' site. It will just have a lot of headroom, manifested as components, that you will most likely not need. Theoretically there's more to go wrong and a higher price you pay for something unnecessary, but thanks to the 80 Plus certification it should be no worse for efficiency.

Based on your preference, I would get the Nexus, as I have not come across reports of or experienced squealing etc. - especially after the nasty RMA experience with Corsair. I also implicitly trust active cooling over semipassive in prolonged use scenarios.

Regarding the Corsair: the review that says it is a Seasonic unit is from 2008. The caveat in the Recommended list clearly states:

Quote:

When it comes to the noise they make, PSUs of the same brand, even of the same series, are not that closely related sometimes. While some PSU brands are pretty consistently quiet (Seasonic is a good example), individual models still vary. Some brands are less consistent. This is especially true of brands whose power supplies are made for them by OEMs, often more than one at the same time, for the same or similar series.

My emphasis. In this instance I would not be surprised to learn that between 2008 and now, Corsair has switched to one of the other subcontractors in their employ, possibly a cheaper, less reputable one.

Regarding how they cut costs, I would claim that it's not the parts that cost the most, but the labour. Skilled, hi-tech assembly labour costs more than cheap, non-skilled, lengthy and tight quality control with large sample sizes costs more than lax, owning your supply chain may cost more than outsourcing etc. The electronic, mass produced parts most likely have cost differences in the tenths of cents and pennies, and as a result will hardly sway prices one way or the other, except in the case of the truly dreadful units where every cent counts. Still, it's probable that lower-rated parts and lower-quality bins would be used by cheaper makers in addition to cutting labour costs.

Warranties are the manufacturers' statements of confidence regarding the product, but when does it stem from the confidence that your product will last the stated span of time, and when does it come from the knowledge that your profit margin allows for a number of busted units and post-purchase customer dissatisfaction? It is probably a bit of both, but I would say the consistent, high-quality manufacturers count on the former first and more than on the latter.

I can't say how much of "Seasonic" goes into a particular design. You'd have to find an expert review for that, like this SPCR review of the VX450: http://www.silentpcreview.com/article751-page3.html for example. I'm just some amateur DIY and silence enthusiast voicing my opinions and the supporting evidence thereof.

I have had excellent experiences with Corsair support (they even sent me a SATA cable for my HX520 for free!), but my experience with their products' consistency and quality has not been the best. Only RAM I have had fail or be incompatible has been Corsair (3 kits, sockets 775 and 939) and OCZ (1 kit, socket 939).

i have one last question. i may wish to add a 2nd GPU at some point to take advantage of GPU rendering. the Nexus seems to have only 2 PCI leads, where the X660 has 4. does this mean i can only power 1 GPU with the Nexus (my 560ti for example would require both PCI leads to power it)?

i have one last question. i may wish to add a 2nd GPU at some point to take advantage of GPU rendering. the Nexus seems to have only 2 PCI leads, where the X660 has 4. does this mean i can only power 1 GPU with the Nexus (my 560ti for example would require both PCI leads to power it)?

Entirely up to the cards you will be using. My old, factory-overclocked 460 GTX only had one for example. If you are serious about multiple cards and think you'll be shelling out for hungrier cards like 670s or whatever AMD has on offer, better get a good number of cables, especially if they are modular and hence won't get in the way. Adapters are available however, and you might be able to get some more cables from Nexustek like I did from Corsair.

I was wondering if the posts were getting too lengthy, but you were plumbing such depths with the questions I thought it best to answer comprehensively.

PS. Dual card setups will essentially triple your system's heat load (not really - what I mean is you'll be adding another component as hot as the current hottest components, so a 50 % increase, but in effect triple the total load compared to a system with a single such heat source) and you may be saying goodbye to silence - or even "quiet", if the GPU coolers take exception to the setup.

Don't forget to check out PSU's from Kingwin and Enermax. The former has quality PSU's that rivals the Seasonic X-series, both in terms of performance and quietness. The latter are less expensive but many of the PSU's are known to have really quiet fans (check out the recommended list).

If you consider a hgh-wattage PSU, then you could consider the Corsair AX750. The AX850 has been reviewed here at SPCR:

i had to make a quick decision as i need to get my pc working again and went with the Nexus. i managed to find the RX-5300 and figured that that will be more than enough for a single GPU setup, and allows plenty of headroom to upgrade the CPU or GPU or both in future.

if i do upgrade to a multiple CUDA card setup for rendering, then i will probably have to upgrade to a bigger PSU too, but i will worry about that once i know exactly what the requirements are.

quest_for_silence wrote:

Just for example, my Enermax 350W PSU has only one 6 pin PCI connector, but it feeds two Gigabyte GTX 460s, which sports 2 6 pin PCI connectors each (I mean through the above mentioned adapters).

interesting, so you have 2 x 460s powered by a 350W PSU?

there seems to be so much misinformation with power 'requirements'. i don't mean you quest_for_silence but for example i phoned Nexus this morning and they suggested that for a 2 x GTX560 setup, i should go for the RX8500 (850W).

now i'm thinking that if i had gone with the 6300 instead of the 5300, i could probably power 2 GPUs. i went with the 5300 because i felt that the extra power would be useless if i couldn't connect an extra GPU. does that make sense?

It makes perfect sense derek. Welcome to the world behind the curtain!

All calculators and recommendations I have seen have been exaggerations at best (present company and context excluded). Luka's/quest's setup is a real champion of light, showing what the real power demands are. The "headroom" calculated into most statements is to ensure customer satisfaction and minimise the risk of losses ("better safe than sorry"), and to my mind stems from an age when PSUs were, shall we say, less consistently reliable (pre 80 Plus).

In the old, wild days no one knew exactly what they were getting, and systems were much less refined than they are now. They certainly were not as standardised (and hence varied in performance figures wildly) as they have become through the 80 Plus program. The expert reviews and education of the public were lacking as well.

You can buy a kW PSU and it will run anything you throw at it. However you will be wasting your money, the extra power circuitry components and efficiency (although the latter is less of a problem post 80 Plus). More than likely any setup, even overclocked (link), even with multiple GPUs (assuming moderate models, link), can be serviced by a 500-ish W rated PSU with 80 Plus qualifications of any level. However you should consider the likely usage scenario (length and level of stress) and the cooling efficiency - and, in SPCR fashion, the noise at a certain power load (%).

PS. Why is efficiency important? Simple: an efficient conversion means more energy into power, less energy into heat (requiring cooling). While it is true that the absolute total amount of heat released will increase as load increases, I'm sure we can all see why it would be best if the PSU provided power, as suggested by its name, and not heating.

there seems to be so much misinformation with power 'requirements'. i don't mean you quest_for_silence but for example i phoned Nexus this morning and they suggested that for a 2 x GTX560 setup, i should go for the RX8500 (850W).

Anything should be done "cum grano salis".

First of all, mine is a temporary solution (the Enermax is my back up PSU): it works well but not enough quietness-wise (as the fan ramps up over a 150-180W DC load). For such a job like mine, you have to carefully choose a quality built PSU, with good regulation as that platform delivers. Don't ask me about Nexus, I can't help: I can only say it's a reputable vendor and there's also a nice review by SPCR.

But as Das_Saunamies has already pointed out, current "popular" power requirements are groundless, pure myths.

For a pair of GTX 560Ti (384 CUDA cores) - which are fairly hotter than the GTX 460s - you may need something below 350W DC at full bore (probably between 310-330W): you can lower these requirements by carefully picking the right card. For example my current Gigabytes GTX 460s are renowned to run "cool", and as a matter of fact I tweaked them to run at 0.862Vcore: as a guessestimate (but well educated) they are pulling something between 170W and 190W (both cards I mean), at least 50W less than normal.

Your Nehalem platform is rather inefficient by today standards: at any rate, according to a somewhat similar SPCR Reference setup, it should account for about 200W DC at full load (you may consider 200-220W DC): as you OC it, I don't think it is easy to undervolt it without incurring in stability issues. But you have to try.

So, AFAIK for one graphic card your total power consumption will be surely under the 400W marks, while with two cards it could be between 510W-550W DC(these are full load figures, but not with synthetic loads like FurMark, which usually stress too much the Nvidia GPUs).

regarding the Nexus, i received and installed it today and so far, so good. it is much quieter than the Corsair (they're not even in the same ball park) and in fact, the loudest fans in the case are now the CPU cooling Noctuas (when on full power).

the only negative with the Nexus compared to the Corsair is the length of the cables, most of which are shorter and so i've had to route some of them inside the main case, whereas with the corsair i could thread them behind the case (between the back panel and the removable back panel), so effectively the case was almost completely free of cables.

more than happy though so thanks to all, especially Das_Saunamies for the help and advice.

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